1. Field of the Invention
The present invention relates to a paper-sheet management method and a paper-sheet management system that perform character recognition of an identification number printed on a paper sheet and use the identification number to manage the paper sheet. The present invention in particular relates to a paper-sheet management method and a paper-sheet management system with which it is possible to perform character recognition of the identification number and search of the registered identification number that has been subjected to character recognition while suppressing an effect of digit shift.
2. Description of the Related Art
A unique identification number that identifies a paper sheet is printed on paper sheets, such as, banknotes, checks, drafts, and gift coupons. In the case of the banknotes, the identification number is called a serial number. Financial institutions require character recognition of the serial numbers of banknotes being transacted to be performed and the serial numbers to be automatically registered in a database. For example, if a counterfeit note is found, the database will be helpful for determining whether the transaction of the counterfeit note were occurred in-house.
To build the database of the serial numbers of the banknotes, it is essential that the serial numbers to be registered as data be correctly recognized. However, in reality, it is not always possible for all the characters composing the serial number to be recognized correctly due to staining, etc., of the banknotes. In such cases, a user has to visually recognize and manually enter the characters that could not be recognized by character recognition. If such unrecognizable characters are in large numbers, the work burden of the user can be rather heavy.
As a solution to the above-mentioned problem, for example, a method of allocating an error character to an unrecognizable character and automatic registration of the serial number is proposed in Japanese Patent Application Laid-open No. 2004-213559. Specifically, if each character of the serial number is considered as a digit, an error character is allocated to each digit that could not be recognized by optical character recognition (OCR), etc., and the recognition process of the serial number is automatically ended, thereby sparing the user manual entry by visual recognition. When it is hard to recognize a character, since an error character can be allocated to the unrecognizable character, misrecognizing can be prevented, and the work burden of the subsequent user can be reduced. A predetermined character, such as, “?” can be used as the error character.
Furthermore, a serial number database building method using error characters and a transaction history management method using serial numbers are proposed in International Publication No. WO2010/032335. In this method, which is developed with an object to reduce the user's work in the character recognition process, an upper limit for the number of error characters is set as a predetermined condition, and the user is only required to perform visual recognition if the condition is not satisfied. Similarly, when searching for a serial number in the database, searching is performed under a predetermined condition, such as, if the number of error characters is within the upper limit or if a particular digit is not allocated with the error character.
However, if there occurs a digit shift of characters of the character-recognized serial number due to staining or scribbling on the banknote, the above-mentioned conventional techniques cannot recognize this digit shift. If such a digit-shifted serial number is registered in the database, the searched serial number cannot be found because of the digit shift. That is, the database cannot be utilized efficiently.
The presence of stains, scribbling, a background design or a colored portion in the front or back of the serial number can lead to miss-recognition of a presence of a character before the actual first character or after the actual last character of the serial number, and to a digit shift of the digits composing the serial number in a right direction or a left direction. There can be many instances where the error character is allocated to a digit because a Roman alphabetic character or a numeric character cannot be recognized even though the stain or scribbling was recognized as a character at the digit position. If the number of the error character is within the range of the predetermined condition, the serial number with the digits shifted is automatically registered as it is in the database without the user having to perform visual recognition.
Specifically, the banknote bearing the serial number “AB123456C” can be misrecognized as “?AB123456C” when there is a digit shift in a right direction. Since this serial number includes only one error character, this serial number is automatically registered in the database without the user performing visual recognition. However, a search for a transaction history of the banknote with the serial number “AB123456C” in the database will yield no result because the serial number that is registered in the database is “?AB123456C”. Because of the digit shift, comparison of each digit will yield no match. The presence of such digit-shifted serial numbers in the database will not be utilized efficiently.